Pressure gauge



Jan. 2, 1943. P. KOLLSMAN 2,309,401

PRESSURE GAUGE Filed March 5, 1941 2 Sheets-Sheet l FIG.I

INVENTOR PAUL KOLLSMAN BY I a ATTORNEY Jan. 26, 1943. P. KOLL SMANPRESSURE GAUGE 2 Sheets-Sheet Filed March 5, 1941 INVENTOR PAUL KOLLSMANBY QM i0 ATTORNEY Patented Jan. 26, 1943 2,309,401 rnnssuau GAUGE PaulKollsman, Greenwich, Comm,

Square D Company, Detroit, Mich.

tion of Michigan Application March 5, 1941, Serial No.

assignor to a corpora- 3 Claims. (Cl. 73110) This invention relates toimprovements in pressure gauges, more particularly to gauges designed toan observer of the gauge.

More particularly, it is an object of this invention to provide animproved manifold pressure gauge for use on aircrait.

The invention funoher aims at providing a pressures the diaphragm sealsthe pressure from one another.

It is a further object of the invention to provide hra'gm. It is afurther object of vide an explosion resistant pressure gauge in- Moreparticularly, the invention aims at providing means for limiting orincreasing the movediaphragm movement.

is another object of this invention to proa highly sensitive explosionresistant presis inexpensive to manufacture, and convenient to adjustfrom It vide easy to calibrate, the outside.

Further aims, objects and advantages will appear from a consideration ofthe description Into the instrument housing there is inserted anexplosion resistant cartridge or casing l6 secured to the rear of thehousing by means of screws 57.

To the flange 26 of the member l8 secured a pressure responsive in theform of a Sylphon or there is member, preferably diaphr tress caused bymounting is avoided in the 111118- The stem extends through the aperture[9 in the bottom of the cup-shaped member l8 forming a dividing wall 33between the chambers 22 and 26. The stem 3| is preferably provided witha curved top surface 34 for purposes later to be described.

The top surface of the stem is engaged by a movable actuating member ofa motion multiplying mechanism arranged in chamber 22.

In the illustrated form of the invention a lever 35 of a rockshaft 36rests against the curved top of the stem. The rockshaft is mounted inpivots 31 and 38 and posts 39 and 40, respectively, on a mounting plate4|.

The rockshaft engages a toothed sector 42 by means of a further lever 43preferably made of a bimetal to compensate for changes in temperature.The sector is mounted in bearings 44 and 45 between the mounting plate4i and the top member or front plate 2| and engages a pinion 46 foractuating the pointer.

In the illustrated form of the invention the movement of the pinion 46is transmitted to the pointer shaft 41 through the pressure resistantwall 2! of the chamber 22 by means of a magnetic coupling comprisingmagnets 48 and 49. A hair spring 50 may be provided for eliminating playin the motion amplifying mechanism and for maintaining the lever 35 incontact with the curved surface 34 of the stem 3|.

The chamber 22 may be filled with a charge of gas of predeterminedpressure, a tube connection being provided for this purpose at 5|. Formanifold pressure gauges it i preferred to evacuate the chamber 22 to ahigh degree after which the tube 5| is tightly sealed.

The pressure responsive member 25 may be acted upon by an adjustablespring. For this purpose the center piece 30 may be formed to include astud 52 for receiving one end of a biasing spring 53. The other end ofthe biasing spring is supported by an adjustable member, in theillustrated embodiment a threaded boss 54 accessible from the outsidethrough the pipe connection 29 into which it is screwed. The boss 54 isprovided with a slot 55 for engagement with a screw driver andpreferably also with a groove 55 permitting an unrestricted equalizationof pressures between the pipe connection 29 and the chamber 26.

By adjusting the tension of the spring 53 the zero position of thepointer may be adjusted in case the pointer should fail to return to itsinitial position on the dial due to aging of the diaphragm. It becomesevident from the drawings that such adjustment does not require accessto the elements of the motion amplifying mechanism which remainpermanently sealed and protected within the pressure chamber 22.Furthermore this adjustment will not disturb the calibration of theinstrument but simply restore the movable wall of the pressureresponsive member to the position which it occupied when the instrumentwas first calibrated.

If an explosion should occur due to ignitio of a combustible gas mixturein chamber 25, Li? diaphragm capsule 25 will be compressed ther yresting its center piece 30 against the flange 20 of the wall 33. Toenhance this sealing action, the flange and the center piece may be soshaped as to form a valve seat and valve member respectively, a conicalvalve being shown at 51 in the flange against which the conical surface58 of the center piece may rest.

The illustrated form of gauge is extremely easy to assemble andcalibrate. The motion amplifying mechanism, as hereinbefore described,is mounted to the top member or front plate 2| which also carries thedial I8 and the dial plate 59 by means of posts 60 and 6!. The mechanismis adjusted to produce a predetermined pointer deflection for apredetermined measuring range by adjusting the stem 3| relatively to thesleeve 32. It will be observed that during this calibration a pressureconduit may be connected to the pipe connection 29 and the diaphragm besubjected to the highest and lowest pressure to which the gauge isdesigned normally to respond. A removal of the front plate 2| for anadjustment of the stem 3| will not affect the pressure in the chamber26.

As hereinbefore mentioned, the surface of the stem engaging the lever 35may be so shaped as to produce an increasing and decreasing movementtowards the beginning or end of the measuring range in response to equalincrements in diaphragm movemen For this purpose the surface of the stemmay be given any desired curvature as illustrated in Fig. 3. In theposition of the stem shown in solid lines, the stem will act on therockshaft 36 at a lever arm Z1. If moved towards'the position shown indotted lines, the lever arm will become shorter as the point ofengagement of the lever 35 and the stem moves from the center of thestem outwardly by an amount Al. The shorter the lever arm 12 and thegreater the distance Al the greater will be the movement of therockshaft about its axis 31, 3B in response to equal increments indiaphragm movement.

After the proper adjustment of the stem 3i has been determined, thechamber 22 may be permanently sealed by soldering at 24 and evacuated,if so desired. Any aging of the diaphragm which will result in failureof the pointer to re turn to its proper zero position may be adjusted,without disturbing the mechanism, simply by adjusting the threaded boss54.

Obviously, the present invention is not restricted to the particularembodiment herein shown and described. Moreover, it is not indispensiblethat all the features of this invention be used conjointly since theymay advantageously be employed in various combinations andsubcombinations.

What is claimed is:

1. A pressure gauge comprising, in combination, a first substantiallycylindrical cup-shaped member having an aperture at the bottomsurrounded by a flange extending outwardly; a top member sealed to saidfirst cup-shaped member to form a first pressure chamber, the firstchamber being evacuated; a diaphragm capsule mounted on said flange; acenter-piece on the movable wall of said capsule extending through saidaperture into said first chamber; a second substantially cylindricalcup-shaped member secured to the bottom of said first member for forminga second pressure chamber therewith enclosing said diaphragm capsule,said second cup-shaped member having a pipe connection; indicating meansmounted to the outer Side of said top member; motion amplifyingmechanism mounted to the inner side of said top member, said mechanismincluding a lever and a spring urging the lever against saidcenter-piece; and a magnetic coupling for actuating said indicatingmeans by said cup-shaped first member having a cyciindrical mechanismthrough a wall of said top member. side wall and a bottom having acentral first aper- 2. A pressure gauge comprising, in combinaturesurrounded by an outwardly exten tion, an explosion resistanthousing,said housing flange, a front cover permanently sealed to said comprisinga substantially cup-shaped first mem- 5 member and forming a firstchamber therewith,

capsule; and a screw threaded plug in said second having a grooveproviding a passage leading from through the bore of the pipe couplingre iv said second chamber to the exterior thereof. to said secondaperture for adjusting the tension pressure gauge comprising, incombinaof said sp ing, said plu having a groove providdow; an explosionresistant housing mounted h er to the base of the pipe coupling.therein, said housing comprising a substantially 45 PA L KOLLSMAN.

